The present invention relates generally to headlights and in particular to headlights having variable beam dimensions.
When a driver operates a vehicle at rapid speeds, especially during nighttime, it is important that the vehicle provides the driver with the ability to see objects far ahead of him. Conversely, when a driver operates a vehicle at slower speeds, it is important that the driver is able to see nearby objects that are in front of him or to either side of him.
Conventional headlights have long been used to improve driver visibility. However, when traveling at fast speeds down long roads, conventional headlights do not often provide sufficient illumination of objects that are relatively distant. In a parking lot or in other locations where the driver should operate the vehicle at slower speeds, it is important for the driver to see objects near to him that are in front of or to the left or right of him. Conventional headlights allow for a driver to have visibility of objects that are nearby and in front of him. However, they do not provide illumination of nearby objects to either side of the driver. Visibility of such objects, such as other vehicles or pedestrians, is important to the safety of the driver as well as other drivers and pedestrians.
It would be desirable to have a headlight that emits a beam of appropriate dimensions (length and width) at various driving speeds to assist in improving a driver""s visibility.
U.S. Pat. No. 4,855,884 to Richardson does provide for a variable beam width light. However, this light is a stage light that relies upon an axially movable reflector for changes in the width of the beam. The reflector comprises slightly spaced apart reflective leaves, forming a bowl shaped structure. A motor driven lead screw engages a base member (supporting the reflector) and as the lead screw is rotated the base member moves to create axial displacement of the reflector and of the lamp present in the stage light. This apparatus is not used in conjunction with a vehicle. It does not take into account the speed of a vehicle and does not use the speed of a vehicle to influence the width or length of a beam of light.
It is thus an object of the present invention to provide a headlight having variable beam dimensions that are dependent on vehicular velocity.
It is an object of the invention to provide a headlight having variable beam dimensions that are dependent upon airflow to a reflector, which is dependent upon vehicular velocity.
It is another object of the invention to provide a headlight having variable beam dimensions that is operated automatically.
It is a further object of the invention to provide a headlight having a variable beam width and length wherein said beam narrows and lengthens as vehicular velocity increases and widens and shortens as vehicular velocity decreases.
It is an object of the invention to provide a headlight having a variable beam width and length wherein said beam narrows and lengthens as airflow to a headlight reflector increases and widens and shortens as airflow decreases.
The above objects have been met by a vehicular headlight having a light source, and a beam forming reflector. The light source directs light towards the reflector which is for example, biased in an open position and which has an aperture whose size is controlled by the velocity of a vehicle or the airflow intensity to the reflector and whose size increases or decreases with velocity. As the velocity increases, the aperture size thus the beam width decreases and the length increases, allowing a driver to see objects far ahead in the distance. As the velocity decreases, the aperture size thus the beam width increases and the length decreases, allowing a driver to see objects nearby and to either side or in front of him.
A further advantage of the present invention is that the changes in beam width and length occur automatically when the car is in operation therefore the driver need not manually make such changes.
In one embodiment of the invention, the reflector comprises a pair of outwardly spring-biased vanes, each vane coupled to an air duct. Airflow through the air duct increases as the velocity at which the vehicle travels increases. When the car reaches a velocity that provides an airflow through the duct that is sufficient to overcome the reflector bias, the reflector vanes move inwardly, thus decreasing the size of the aperture and decreasing the width of the beam. Conversely, when the vanes are in a position where the bias has been overcome, as the car decelerates the reflector aperture widens and the beam width widens as the vanes give in to the bias of the spring. As the beam width widens, the length decreases. As the beam width narrows, the length increases.
In another embodiment the reflector is conical in shape and includes a spring-biased radial arm varying the reflector aperture size. An air duct is coupled to the radial arm. The cone may be tightened or loosened by the radial arm under the influence of the air duct. Airflow through the air duct increases as the velocity at which the vehicle travels increases. When the car reaches a velocity that provides airflow through the duct that is sufficient to overcome the spring bias the radial arm tightens, thus decreasing the size of the aperture and decreasing the width of the beam and increasing the length. Conversely, when the radial arm is in a position where the bias has been overcome, as the car decelerates the reflector aperture widens and the beam width widens as the radial arm gives in to the bias of the spring.
In a further embodiment of the invention a velocity sensor of the vehicle provides a signal to the reflector. When the speed reaches a certain level the reflector receives a signal that causes, through an actuator, the reflector to either narrow its aperture so that the beam that emerges from the aperture is narrowed and lengthened or to widen its aperture so that the beam that emerges is widened and shortened.
In another embodiment of the present invention the position of the light source may be varied in response to a signal received when the velocity reaches a certain level thus affecting the size of the beam emitted from the reflector aperture. When the velocity of the vehicle increases the light source is moved away from the aperture, thus narrowing the beam of light. When the velocity of the vehicle decreases the light source is moved toward the aperture, thus widening the beam of light.